When I create a table in Contribute 2, it is by default
"box-y" - hard square edges. Looks very 1991-ish to me. I want to
round out the edges, like the tables in iTunes, or even the
sidebars on the Macromedia Homepage. Can this be done. If so, how?

Tables will have square corners unless you insert images (via
CSS typically) that give the table a rounded corner appearance.
Contribute will only show what the code is asking it to show, so
it's up to you as to how to add the corners. Here is an example of
a page that shows this concept:
http://www.rrps.net.

Alternately, you can use CSS to apply a mozilla-based value
to a DIV element (works only in Firefox, possibly in Opera at this
time) that looks like this:
-moz-border-radius: 15px;

You would just change the pixel value to get a different size
corner. Here's a page that shows this (if you have Firefox):